/Engine/Source/Editor/MovieSceneTools/Public/Sections/ThumbnailSection.h
Thumbnail section, which paints and ticks the appropriate section.
class FViewportThumbnailSection : public [FThumbnailSection](API\Editor\MovieSceneTools\Sections\FThumbnailSection), public [IViewportThumbnailClient](API\Editor\MovieSceneTools\TrackEditorThumbnail\IViewportThumbnailClient)